The essence of this methodological study is the validation of a comprehensive measure of suicide potential for adolescents. Prevention science is currently severely hampered by inadequate instrumentation for assessing suicide risk among youth. Thus, the objectives of this study are to: l) further establish the validity and reliability of the Measure of Adolescent Potential for Suicide (MAPS) employing a large representative sample of vulnerable youth; 2) derive an index for summarizing suicide potential among vulnerable youth; and 3) evaluate a Suicide Risk Screening (SRS) protocol for identifying youth in need of comprehensive assessment and intervention. A 2-staged survey-interview design will be used to: l) establish reliability and validity of the indicators for each key MAPS dimension-- Suicide Risk, Related Risk and Protective Factors; 2) evaluate convergent/divergent validity of 3 key MAPS dimensions using a separate measurement model for each; 3) test and validate, using a split sample approach, the hypothesized full MAPS measurement model; 4) test for differences within the full measurement model in factor structure and Potential for Suicide means across groups stratified by age and sex; 5) explore for differences in Risk and Protective factors, variation in MAPS factor structure, and reliability and validity coefficients based on subsamples stratified by ethnicity; 6) using a split sample approach, test/evaluate a scoring method for a summary MAPS Index; and 7) establish preliminary sensitivity and specificity of the SRS protocol. The analyses are designed to critically evaluate the MAPS and the theoretical measurement model from which it is derived. Analyses include tests to establish reliability and validity coefficients, confirmatory factor analyses using structural equation modeling, discriminant analyses, receiver operating characteristic curves for comparing scoring methods, and classification and regression tree analysis. Subjects will be 768 "vulnerable" youth in grades 10-12, ages 15-18, from 5 high schools. Vulnerable youth will be defined as being at high-risk of school dropout and will be sampled from the school population using a previously validated case-finding strategy. Short term, this study will provide detailed knowledge of the measurement qualities of the MAPS and the effectiveness of the suicide risk screening protocol, the SRS. This knowledge is essential for refining and fine- tuning the MAPS interview and SRS, which will in turn enhance our capacity to identify youth at risk for suicide. Long range, the validation of the measurement model, the MAPS and the SRS will provide a blueprint for designs of preventive intervention studies. These tools and the methodology surrounding their development will advance the interdisciplinary science of adolescent health promotion through greater understanding of suicide risk potential and by providing instruments for evaluating preventive interventions or suicide behavior in adolescents.